Analysis on Heavy Metal Concentrations in Primaries of Whooper Swan in Overwintering Stages of Different Years From Yellow River Wetland in Sanmenxia of Henan Province, China

To assess levels of heavy metals exposure in whooper swan (Cygnus cygnus) adults and juveniles from Yellow River wetland in Sanmenxia, primaries collected in overwintering stages of different years from 2001 to 2017 were analyzed using wet digestion method. Then, atomic absorption spectrophotometer was employed to determine the concentrations of copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), chromium (Cr) and nickel (Ni). Results show that Zn levels were at highest whereas Ni levels were at lowest in primaries from both juveniles and adults. Differences were noted among heavy metal concentrations in primaries of whooper swans from different years. Concentrations of Cu, Pb and Cd in primaries of whooper swan juveniles in 2013 showed a downtrend and Zn concentrations showed an uptrend compared with those in 2001. Moreover, Cr and Ni concentrations in primaries of whooper swan juveniles in 2013 were comparable with those in 2001. In recent years, Cu and Cr concentrations in whooper swan adults were comparable with those of past several years, while Zn, Pb, Cd and Ni concentrations showed a downtrend. In addition, adults and juveniles showed comparable Zn concentrations in primaries. However, concentrations of Cu, Pb, Cd, Cr and Ni in primaries of whooper swan adults were higher than those of juveniles. All in all, as non-essential elements, Pb and Cd concentrations in primaries of whooper swan adults and juveniles showed declined tendencies in recent years, indicating there are decrease trends of Pb and Cd exposure risks. At last, heavy metal concentrations in primaries of whooper swan were at safe levels compared with other birds' feathers.